Supporting elements of this type are used primarily for clamping a work piece in machine tools. Labile work pieces require for their clamping generally more than three support points. Support elements suitable for providing the support points are movable and must gently contact the labile work piece to avoid displacing the work piece out of a located position. The term "located position" in this context means that the work piece has been located in a precise position relative to a three dimensional coordinate system in preparation for a machining operation, for example. Labile work pieces are sensitive in this respect because due to their lability, they have a tendency to again move out of a located position. The gentle movement of a support into contact with a located work piece can be accomplished in a practical way only with an adjustable force. On the other hand, it is necessary that the work piece is held in the located position by the pin during the entire machining operation.
Support elements are known in which the pin is adjusted into a work piece contacting position by screws, wedges, springs, or a hydraulic drive. The clamping of the properly positioned pin then takes place through a piston cylinder device or through expandable tapes. Generally, these procedures of contacting and clamping take place automatically.
However, especially in connection with labile work pieces a consistently repeatable sensitive adjustment of the contacting force is required to avoid moving the once located work piece out of its located position. This condition is not satisfied by known support elements. Further, it is necessary that each support element is individually adjustable and readjustable at any time.